1. Field of the Invention
The invention is directed to a hydrodynamic coupling device having an impeller wheel, a turbine wheel, and a lockup clutch with an axially movable piston and a torsional vibration damper.
2. Description of the Related Art
A prior art hydrodynamic coupling is disclosed in German reference DE 196 17 409 Al, particularly in FIG. 1. This reference describes the hydrodynamic coupling device in the form of a torque converter having, among others, an impeller wheel and a turbine wheel which, together with a stator wheel, form a hydrodynamic circuit. Further, there is provided a lockup clutch having an axially movable piston and a torsional vibration damper which has elastic elements in the form of springs extending in the circumferential direction. Bent portions are provided at the piston as well as at a ring fastened to the turbine shell for the purpose of driving these elastic elements, wherein the bent portions at the ring act as first driving means for the elastic elements and the bent portions at the piston act as second driving means. The torsional vibration damper is active when the lockup clutch is closed, i.e., when the piston contacts a friction surface of a primary flange of the clutch housing via a friction facing. Torsional vibrations present at the clutch housing are superimposed on the torque and are conducted via the piston to the elastic elements. From the elastic elements, the torsional vibrations are conducted to the turbine via the ring fastened to the turbine shell. In turn, the turbine, in a known matter, conducts torque and damped torsional vibrations via the turbine hub to a driven shaft which acts as a transmission input shaft. With respect to the flow of torque, the piston acts as a drive-side transmission element of the torsional vibration damper and the ring fastened to the turbine shell acts as a driven-side transmission element of the torsional vibration damper.
As can be seen from the hydrodynamic coupling device according to FIG. 1, this prior art hydrodynamic coupling device is extremely wide in the axial direction and is therefore not suitable for installation in compact automobiles where there is usually only limited installation space. In this regard, it is noted in particular that the hydrodynamic circuit is particularly wide as a result of the intermediate arrangement of a stator wheel between the impeller wheel and turbine wheel on the one hand and, on the other hand, as a result of the arrangement of the lockup clutch including the torsional vibration damper axially alongside the hydrodynamic circuit, much installation space is taken up in this direction.